Genetic Diagnosis for Marfan syndrome

What is Marfan syndrome?

Marfan syndrome is both a connective tissue disorder, and a congenital disorder, meaning present at birth, but the full range of its symptoms do not often develop until later into childhood, or even early adulthood in some cases. 

Symptoms of the syndrome generally affect the skeletal, ocular (the eyes), and cardiovascular systems of the body. 

It is an inherited condition, in around 75% of all diagnosed cases. The remaining cases are the result of spontaneous, and new genetic mutations. The syndrome is inherited in an autosomal dominant pattern of inheritance, meaning only one parent needs to be a carrier of the gene mutation to have a 50% chance of passing the syndrome onto their child.


The following symptoms, either at birth or later in childhood may lead to a diagnosis of Marfan:

  • Thin and tall stature
  • Exceptionally long arms, and legs
  • Scoliosis (curving of the spine)
  • Hyper-flexible joints
  • Congenital heart defects
  • Ocular issues (affecting the eyes)

Genetic diagnosis for Marfan, what you need to know

Genetic diagnosis for Marfan syndrome may involve a combination of genetic testing, and diagnosis based on an individual’s symptoms. 

Marfan syndrome genetic testing involves a blood test, used to identify mutations in the FBN1 gene. This gene is the cause of the majority of cases of Marfan. However as this testing is complicated, and does not always result in a straightforward diagnosis, it is important for an experienced genetic counselor to be involved in the process. 

In some cases, blood testing may diagnose a different syndrome, including Loeys-Dietz, which has similar symptoms to Marfan. This can all be fully explained by a genetic counselor. 

Genetic diagnosis for Marfan, genetic counseling

Genetic counseling will:

  • Emotionally support rare disease patients and their families through the genetic testing process. This is especially important when it comes to Marfan syndrome due to the complexities of testing for mutations in the FBN1 gene. Genetic testing might not prove to be as conclusive as parents expect, and the road to reaching a diagnosis might turn out to be longer and more challenging than anticipated or expected. Genetic counseling can prepare parents for this eventuality, and support them throughout the entire process. 
  • Help parents understand the different options for testing (including diagnostic genetic testing options) what each type of testing involves, and how to make sense of the results received following testing. 
  • Explain the symptoms of the syndrome, including recommendations for early intervention and treatment, and understanding the symptoms better, in order to ensure a more accurate diagnosis.
  • Help coordinate the medical staff and professionals involved in the care of someone with Marfan syndrome. This will vary depending on the severity of each individual’s specific symptoms. 
  • Understand the inherited nature of the syndrome, and if other siblings should be tested, and if carrier screening is recommended for the parents. 
  • Understand more about the family medical histories of both parents, and how this might help them reach a more accurate diagnosis of Marfan syndrome. 

A genetic diagnosis of Marfan syndrome will be difficult to process for many families. Access to expert genetic counseling is imperative for anyone facing a diagnosis of Marfan syndrome in their family.

Genetic diagnosis involving Marfan syndrome will have a life-long impact on a family, and potentially impact on the planning of future pregnancies as well. Understanding what all of these implications mean, is something a genetic counselor can do.


FDNA™ Health can bring you closer to a diagnosis.
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